The present invention relates to turbomachinery, and more particularly to a shaft design for turbomachinery.
The rotating shafts of turbomachinery are supported from a non-rotating structure by arrays of anti-friction bearings. In many engines, anti-friction bearings are enclosed in bearing compartments that allow the anti-friction bearings to be more easily lubricated and cooled.
Bearing compartments can be sealed around the shaft by various types of seals including a rotary face seal assembly with a seal element and a mating ring. The mating ring is mounted on the shaft to rotate therewith and has a contact face which slidably engages and interfaces with the stator carbon seal. In many cases, the carbon seal is movable (axially relative to the shaft) against and away from the mating ring by springs and air pressure. Typically, the interfacing surfaces that comprise the contact faces of the mating ring and the carbon seal are lubricated to minimize friction and wear.
The bearing and other components of the bearing compartment including the carbon seal and the mating ring are cooled and lubricated by oil supplied from other locations in the gas turbine engine. Typically, this oil weeps out from the cooperating seal faces and the oil must be removed or scavenged utilizing various techniques. Excessive weepage of oil from the bearing compartment is not desirable.
One construction utilizes a nut which places the mating ring in compression against a shoulder of the shaft. This configuration results in forces that deflect the shoulder and mating ring in an axial direction relative to a centerline of the shaft. The deflection of the mating ring results in tilting and/or distortion of the contact face of the mating ring relative to the contact face of the carbon seal. This misalignment of the contact faces results in excessive wear of the sealing contacts and/or weepage and loss of oil from the bearing compartment.